Abrasive wheel and mounting



April.l3, 1937. 'j H. wfHf BETH 2,076,806

ABRASIVE WHEEL AND MOUNTING Fild Jan. 4, 1956 I HuBEI W. H. BE TH Patented -Apr. 13, 1937 PATENT OFFICE 2,076,800 i ABRASIVE wnnnr. nun MOUNTING Hugo W. 1!. Beth, Worcester, Mass., assignor to Norton Company, Worcester, Man, a corporatlon of Massachusetts Application January 4, 1936, Serial No. 57,621

13 Claims. 51-209) The invention relates to abrasive wheels and mountingsttherefor; a

One object oftheinvention'is toprovide an abrasive wheel and mounting adapted to withstand a high degree of heat during grinding. Another object of the invention is to provide an abrasive wheel and mounting with provision for the differ- I ential between the coefficient of expansion of the wheel substance and the mounting substance. Another object of the invention is to provide a stronger union between the abrasive wheel and mounting under varied conditions of practical use. Another object of the invention is to provide an improved mounting plate for an abrasive wheel. Another objectof the invention is to provide a construction for an abrasive wheel and mounting facilitating assembly. Another'object of the invention is to provide an integral side face grinding wheel united to a metal backing plate with a tough and strong union adapted to withstand a high degree of heat. Other objects will betin part obvious orin part pointed out hereina er. 1

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts as will be exemplified in the structure to behereinafter described, and the scope of the application of which will be indicated (in the following claims.

, In the accompanying drawing in which is shown one of the various possible embodiments of the mechanical. features of this invention,

Figure 1 is a plan view of a mounting plate constructed in accordance with the, invention;

Figure 2 is a cross sectional view taken on the line 2-4 of Figure 1 of the mounting plate ofFigure 1 'with an abrasive wheel attached thereto.

As conducive to a clearer understanding of the present invention, it is notedthat there are particular grinding purposes for which a wheel grinding on a radial surface, which may be annular or otherwise, is preferred. It isioften a requirement in such a grinding operation that there shall be nothing projecting beyond the plane of the grinding face in thedirection away from the supporting spindle or other supporting means. To mount such grinding wheels there have been hitherto proposed both soft and hard rubber as a cement uniting the wheel to}. beckinsplate which can be readily attached to a spindle.v Bysoft rubber is meant a rubber vulcanized with a relatively small amount of sulphur which rubber 1 is reasonably resilient. By hard rubber is meant that substance sometimes called ebonite which 5 is vulcanized with a larger amount of sulphur,

V pensive and may be readily cut to provide the speusually 20% or more, and which is relatively rigid. Hard'r rubberphas an;:;.advanta8&:-0ver soft rubber in that it has greater tensile strength, andno cement however great itsproperties of adhesion can be any stronger than the coherence of its particles to each other. Hard rubber has L the further advantage that it is less susceptible to thermal effects, and sometimes wheels such as herein mentioned are caused to do so much work that overheating occurs, therefore making the resistance to heat of the cement a factor of importance. On the other hand, as a steel or iron backing plate is usually used on account of its strength and other desirable qualities, and as the coefllcient of expansion of steel or iron is diiferent from that of many grinding wheels, the soft 1 rubber has had the advantage that, being'resilient, differences of coeflicient of expansion become immaterial while hard rubber, having no such resilient or plastic qualities, or to a lesser degree, there has been experienced rupturing of the cement in cases where the diameter of the wheelwas large. A

Referring now to the illustrated embodiment of the invention and more particularly to Figure 2, I'provide a grinding wheel Ill shown as a cy- 25 lindrical annulus, the radial face I I being a grinding face. This-grinding wheel I0 is to be secured to a spindle l2 having an integral disk-like flange I3 with a. plurality of tapped holes II. .The spindle I! may be mounted in any suitable bearings and rotated'in any suitable manner and may be part of a complete machine, not shown. There is no particular significance to the orientation of the axis of the spindle I! in the presentdrawing, and'actually the spindle'l! might be inverted from the position shown, or might be horizontal, or might be positioned in any other position desired.

I provide a metal backing plate liwhose area is preferably the same as the area of the outside circle of the annular grinding wheel "I. This plate I5 is desirably a steel plate, since steel provides the desired strength, is relatively inexcia-lfeatures now to be described. By means of a suitable die or in any other desired manner I cut a series of arcuate slots "in the plate It. These slots it are located arounda circle, are discontinuous from each other, and leave an apprexciable arc of metal i1 between each adjacent slot. In another circle, and as shown in a circle of lesser radius, I provide a second series of inmate slots ll, each subtending substantially the same ing a substantial arc of metal l9 between them.

As the circle of the slots 8 is spaced from the circle of theslots It by a substantial distance, it

will be seen that the plate is continuous from the 6 central hole 20 therein to the periphery along,

however, irregular lines. Preferably I provide radial slots 2| from the periphery of the plate l5 to the slots l6 and preferably meeting the slots l6 at the mid points thereof. The plate i5 also 10 has a plurality of screw holes 22.which may be countersunk as shown and which are arranged to match the tapped holes I. The central hole may be omitted if desired, but it is provided if the flange l3 has a centering projection 23.

Any portion of the backing plate or disk l5 which is substantially bounded by any of the slots specified can be moved a limited distance in any direction parallel to the plane of the faces of the disk l5. There is a certain amount of give to 20 hard rubber so that, for areas whose greatest linear dimension does not exceed a certain size, a metal plate and a grinding composition secured together by hard rubber presents no rupturing possibilities over a given range of temperature, whereas, in larger sizes, the same grinding composition and the same type of plate secured by the same hard rubber cement might separate by cracking of the cement upon cooling of the article from the vulcanizing temperature, owing to the differential in coefficients of expansion, and on account of inability of the rubber to conform itself to-relative movement of a portion of the plate and a portion of the composition over such a great linear distance.

It will be seen that a plate made as described presents definite areas marked which are almost, if not quite, islands with respect to the central body portion 25 of the plate, the joining metal 21 being narrow and therefore flexible. As the greatest dimension of the areas 25 is still less than the limiting dimensions so far as rupturing is concerned, when the invention is embodied in theiorm of. a vitrified grinding wheel and a steel plate not greater than 24 inches in diameter, danger of rupturing on account of diflerences of coefiicient of expansion is avoided even when using a hard rubber 'cement. For wheels and plates of larger diameter than that just specified, a greater number of arcuate slots l5 and a greater number of slots 2| may be provided. Not only may the islands 25 move with respect to the body portion 26, but it is noted that due to the disposition of the slots, motion in a radial line is relatively freer than motion in a circumstresses that have caused the greatest difllculty.

Having provided an annular wheel I and a steel backing plate l5 as described, I secure the-"1 together with hard rubber cement 30 in the ft.- lowing manner. Sand blasting one side of the plate I5, I place a thinsheet (for example of s inch thick) of vulcanized hard rubber composition, being milled rubber containing 20% or more of sulphur, upon the plate l5, and then place the grinding wheel l in matching relationship upon the rubber, and secure the parts together with ordinary screw clamps. I prefer to use a number of clamps equal to the islands 25 so that each one of them will be in intimate contact with the rubber. I prefer to locate the clamps so that they cross the slots 2| or else provide double the number of clamps so that each portion 25 will be secured at both edges, and it ferential direction, and it is the relative radial rubber composition between them in the vulcanizing oven and vulcanize at a. temperature and for a length of time which is well understood by those cognizant of the manufacture of hard rubber, for example fourteen hours at C.

The wheel and plate are now securely fastened together and in the cooling of the combined article from vulcanizing temperature cracks do not appear on account of the features of construction already explained. The plate may be readily secured by means of screws 3| to the flange l3, and may as readily be detached therefrom. It will be understood that many other cements may be used besides the ordinary'hard rubber composition comprising rubber and sulphur, and the I be subjected to such severe operations that great heat is generated without in any way disrupting the union between plate and wheel or endangering the plate. Furthermore if the wheel III does break, its portions are held to the backing plate I 5 so that they will not fly out.

While vitrified wheels may be particularly mentioned, the invention is likewise applicable to other types of grinding wheels, such as silicate bonded grinding wheels, cement bonded grinding wheels, rubber, shellac, and artificial resin bonded grinding wheels, and any abrasive material whatsoever may be used to form the grinding wheel.

It will thus be seen that there has been provided by this invention an article. in which the various objects hereinabove set forth. together. with many thoroughly practical advantages are successfully achieved. ,As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood'that all matter hereinbefore set forth, or illustrated in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. A combination grinding wheel and backing plate comprising an abrasive annulus, a metal plate secured thereto, said plate having arcuate slots therein, and a cement joining the annulus to the plate.

3. A backing plate for grinding wheels having arcuate slots in a circle.

3. A backing platefor grinding wheels having arcuate slots in a plurality of concentric circles.

4. A backing plate for grinding wheels having radial slots.

5. A backing plate for grinding wheels having arcuate slots in two concentric circles in staggered relation. i

6. A backing plate for grinding wheels having arcuate slots in two concentric circles and radial slots.

8. A plate. as claimed in claim 2 having a grindingwheel cemented thereto with a tough.

cement.

9.. A plateas claimed in claim 3 having agrlnd 10 A plate as claimed in claim 4 having a ing wheel cemented thereto with a tough cement.

grinding wheel cemented thereto with a tough cement. 1

11. A plate as claimed in claim 5 having a grinding wheel cemented thereto with a. tough 5 cement.

12. A plate'es claimed mcmmi 6 having a 

